Total or near-total occlusions in arteries can prevent all or nearly all of the blood flow through the affected arteries. Chronic total occlusions (CTOs) can occur in coronary as well as peripheral arteries. It has been estimated that approximately 10% of all angioplasty procedures are currently undertaken for CTOs.
In the past, a number of devices have been developed and/or used for the percutaneous interventional treatment of CTOs, such as special guidewires, low-profile balloons, laser emitting wires, atherectomy devices, drills, drug eluting stents, re-entry catheter, etc. The factor that is most determinative of whether the interventionalist can successfully recannalize a CTO is the interventionalist's ability (or inability) to advance a suitable guidewire from a position within the true lumen of the artery proximal to the CTO, across the CTO lesion (i.e., either through the lesion or around it), and then into the true lumen of the artery at a location distal to the lesion.
In some instances, such as where the occlusive matter is soft or where the occlusion is less than total, the guidewire can simply be pushed through the occlusive matter itself, thereby allowing the guidewire to remain within the artery lumen. However, in other cases, such as where the artery is totally occluded by hard, calcified atherosclerotic plaque, the guidewire may tend to deviate to one side and penetrate through the intima of the artery, thereby creating a neo-lumen called a “subintimal space” (e.g., a penetration tract formed within the wall of the artery between the intima and adventitia). In these cases, the distal end of the guidewire may be advanced to a position distal to the lesion but remains entrapped within the subintimal space. In such instances, it is then necessary to divert or steer the guidewire from the subintimal space back into the true lumen of the artery at a location distal to the CTO lesion.
Copending U.S. patent application Ser. No. 11/613,764 entitled Low Profile Catheters and Methods for Treatment of Chronic Total Occlusions and Other Disorders describes a low-profile catheter device that may be useable to facilitate passage of a guidewire from the subintimal space into the true lumen of the blood vessel and related methods for bypassing CTOs.
A number of other catheters known in the prior art may also be useable to redirect subintimally entrapped guidewires back into the true lumen of the artery. Included among these are the devices described in U.S. Pat. Nos. 5,830,222 (Makower), 6,068,638 (Makower), 6,159,225 (Makower), 6,190,353 (Makower, et al.), 6,283,951 (Flaherty, et al.), 6,375,615 (Flaherty, et al.), 6,508,824 (Flaherty, et al.), 6,544,230 (Flaherty, et al.), 6,655,386 (Makower et al.), 6,579,311 (Makower), 6,602,241 (Makower, et al.), 6,655,386 (Makower, et al.), 6,660,024 (Flaherty, et al.), 6,685,648 (Flaherty, et al.), 6,709,444 (Makower), 6,726,677 (Flaherty, et al.) and 6,746,464 (Makower). One such catheter is currently available as the Pioneer™ catheter from Medtronic Vascular, Inc., Santa Rosa, Calif.
There remains a need in the art for the development of new small diameter catheters that have laterally deployable members (e.g., cannulae, needles, probes, wires, etc.) which may be used to re-enter the true lumen of a blood vessel when bypassing a CTO for other purposes such as delivery of substances, articles or devices to specific target locations within the body.